Tubular hypodermic needle



Dec. 6, 1966 R. P. DUNMlRE ETAL TUBULAR HYPODERMIG NEEDLE Original FiledDec. 8. 1961 5 Sheets-Sheet 1 28- w m .4p 8 22 1 HHIIII 35 L24 56 38FIG. 39

42 FIG. 4

FIG. 5

HANNAH DUNMlRE,Execufrix of The esfafe of RUSSELL I? IN V EN TORY)ATTORNEYS 1966 R. P. DUNMIRE ETAL 3,289,675

TUBULAR HYPODERMI C NEEDLE Original Filed Dec. 8, 1961 5 Sheets-Sheet 2INVENTORS HANNAH DLJlVIMlRL-f Execufrix of The estate of RUSSELL HDUNMlRE deceased and HARRY c, EBY

VATTVORNEYS 1966 R. P. DUNMIRE ETAL 89,675

TUBULAR HYPODERMIC NEEDLE Original Filed Dec. 8. 1961 5 Sheets-Sheet f5l I I I 56 56b 28 I I 4 I 6/0 *4 I I 6/- l \'../\./\UJ,. k.-- 9 12% w 7'/I" FIG, 8

INVENTORD HANNAH DUNMlRggxecufrix of the estate of RU ELL P DUNMIRE,deceased and HARRY Cv EBY 1 United States Patent 3,289,675 TUBULARHYPODERMIC NEEDLE Russell P. Dunmire, deceased, late of Chagrin Falls,Ohio, by Hannah Dimmire, executrix, Chagrin Falls, tibia, and Harry C.Eby, Meadville, Pan; said Eby assignor to said Hannah Dunmire, executrixOriginal application Dec. 8, 1961, Ser. No. 158,944, now Patent No.3,173,200, dated Mar. 16, 1965. Divided and this application May 25,1964, Ser. No. 374,870 14 Claims. (Cl. 12t5--22ll) This application is adivision of a copending current application Serial No. 158,944, filedDecember 8, 1961, now Patent No. 3,173,200, for Sharp-Edged MetalArticles and Methods of Making the Same, said parent application havingthe claims thereofrestricted to the method disclosed therein, and thepresent divisional application being directed to the sharp-edged metalarticles.

This invention relates to the manufacture of a wide variety ofsharp-edged metal articles, including hypodermic needles, surgicalneedles, sutures, and other acute medical instruments intended to beinserted through the epidermis. More particularly, the present inventionis concerned with the manufacture of improved hypodermic needles adaptedfor use in disposable injection devices of the type disclosed in U.S.Patents Nos. 2,696,212 and 2,769,443 granted to Russell P. Dunmire onDecember 7, 1954, and November 6, 1956, respectively.

Heretofore, the general procedure for producing sharpedged articles, andparticularly pointed medical instruments of the type described, has beento form the body of the article from a suitable metal, which usually isin an annealed condition, and then to harden the metal and secure acutting edge by a plurality of grinding operations. In the case ofhypodermic needle manufacture, this conventional procedure has commonlyinvolved the steps of producing hot-rolled seamless tubing fromstainless steel or other metal and cold drawing the tubing to thedesired diameter and wall thickness. everal cold drawing passes wererequired to reduce the hot-rolled tubing to the desired size, it beingnecessary to heat treat, pickle, and lubricate the tubing after eachpass.

Following the cold drawing operations, the tubing was cut intoappropriate lengths and an end of each length ground to a point. Themost common point configuration has been a simple bevel formed on theend of the tube by first rough grinding the end of the tube to lie in aplane at an angle to the longitudinal axis of the tube, then finishgrinding or honing the bevel point, and finally deburring the point.

Even though the foregoing procedure has been the accepted method ofmanufacturing hypoderi-mc needles for a number of years, it has longbeen recognized as an expensive, time-consuming procedure, frequentlyresulting in improperly formed needles which cannot be used toadminister an injection satisfactorily and which cause eX- cessive painto the patient, including, in many instances, pyrogenic effects. Forexample, it will be seen that the very configuration of theconventionally ground bevel point is not conducive to a painlessinjection, since the flat surface of the point presents the full metalthickness of the needle wall to the skin rather than an advantageous,sharp cutting edge after the sharp, extreme tip has cut an initial slit.As a result, the conventional needle punctures and tears its way intothe skin during the balance of its penetration.

As indicated above, the conventional grinding operations usually formboth inner and outer turned-over burrs around the edges of the groundend of the needle. These metal burrs must be removed; otherwise they maybreak away and lodge in the skin or subcutaneous tissue and producesoreness and swelling. The usual deburring methods which have beenresorted to are time-consuming and expensive and are not completelysuccessful. Moreover, they tend to dull the point and to anneal andsoften the metal sothat the points are fragile and may be relativelyeasily damaged during shipping and handling prior to use.

In attempts to reduce the costly manufacturing operations which areinvolved in producing hypodermic needles 'rorn seamless tubing, it hasrecently been proposed to fabricate the needles from flat, fullyannealed, metal blanks by bending the metal blanks into tubular form. Ithas also been proposed to form the blanks with triangular end portionswhich form the pointed end portions of the needles when the blanks arebent into tubular shape. In order to produce a satisfactory needle inthis manner, however, the point must subsequently be hardened by heattreating and then be ground by the usual grinding techniques in order toobtain a sufiiciently sharp point. Such grinding has produced aconventionally beveled point and perpetuate-d the above-discussedproblems and draw-backs inherently involved in the more conventionalmethod of producing needles from seamless tubing.

It will be appreciated that the desirability of having sharp, accuratelyformed, hypodermic needles is accentuated when the needles are intendedfor use in disposable types of injection devices for self-administrationof injections, such as the types disclosed in m above-identifiedpatents. This special need for the needles to be sharp and accuratelyformed so as to make their insertion as safe and painless as possible,is due to the natural aversion and apprehension which many peopleexperience when giving themselves injections, and also to the fact thatmost persons are not trained to administer injections in the mostefificient manner.

The particular type of self-injectiou devices common to the disclosuresof US. Patents Nos. 2,696,212 and 2,769,443 of Russell P. Dunmirepresent still another problem. The needle in such devices is completelycontained within an ampoule shell in such a position that, when thedevice is used, the pointed end of the needle is forced through a wallor diaphragm of plastic or the like and into the skin. Whenconventionally formed needles are used for this purpose, they frequentlycause what is known as coring; that is, the passageway through theneedle is plugged by a piece of material severed from the diaphragm orwall that is pierced by the needle. This severed piece of material maycompletely clog the needle so that it is virtually impossible to ejectfluid through it. More frequently, the cored material is forced from theneedle by the hypodermic liquid and is lodged beneath the skin. Whenthis happens, such foreign material, as in the case of metal burrs, maycause soreness and swelling, including pyrogenic efi'ects.

An object of the present invention is to provide sharpedged metalarticles, such as pointed hypodermic needles and other acute medicalinstruments and the like, which are characterized by hardness andsharpness of their cutting edges and points and by accurate, uniformlyproduced shapes.

Another object of the invention is to provide improved hypodermicneedles which have desirable characteristics mentioned above and whichare particularly adapted for use in self-injection devices.

Still other objects of the invention are to provide sharpedged metalarticles and, particularly, hypodermic needles of a design capable ofbeing produced automatically from metal stock by mass productiontechniques at high speed and low cost; and to provide hypodermic needleshaving pointed ends of such a character and configuration as to maketheir insertion into the patient as safe and painless as possible.

While it is to be understood that the invention, in its broadestaspects, is not limited to hypodermic needles, the construction of suchneedles in accordance with the invention is considered to exemplify bestthe marked advantages which are afforded by the invention. Therefore,the invention will hereinafter be more particularly described inrelation to hypodermic needles.

In accordance with the invent-ion, hypodermic needles may be fabricatedfrom fiat, annealed, strip stock in a continuous operation whichincludes the steps of forming blanks having substantially rectangularcannula forming strips with wedge or triangular shaped end portions, andthen bending each such strip into tu bular shape with its side edges inabutment. In order to eliminate the disadvantageous grinding steps andattendant operations of the prior art, the invention contemplatesselectively hardening and thinning the metal of the strip portions ofthe blanks in their wedge-shaped end portions, preferably prior tobending the blanks into finished form, although the invention is notnecessarily restricted to employing such an order of fabrication steps.

According to the invention, the hardening of the tips or wedge-shapedends of the blanks may be expeditiously accomplished by work hardeningsmall areas of the strip stock before the blanks are severed therefrom.One advantage of selectively hardening the metal in this manner is thatthe relatively soft cannulae of the needles can be formed by one or morebending operations without intermediate heat treating steps as requiredby prior art methods. Another advantage is that the hard, sharp edgesand points of the nee-dles can be formed in a single, economicaloperation with improved accuracy, precision, and uniformity.

In addition to having sharp, hard points, the uniquely shaped pointedend portion of hypodermic needles manufactured according to theinvention is characterized by sharp, inner and outer, peripheral,cutting edges. The conventionally ground point formation, as notedabove, presents the full cross-sectional thickness of the needle wall tothe skin during penetration so that the end of the needle must be forcedthrough the skin with an often painful punching action. As distinguishedtherefrom, inner and outer peripheral cutting edges provided by thepresent invention act to separate the skin with a progressive cuttingaction during penetration so that the needle may be smoothly and quicklyinserted with a minimum amount of discomfort and irritation.

When the hypodermic needles of the invention are used in disposable,self-injection devices of the types referred to above, the configurationof the pointed ends of the needles also has been found to substantiallyeliminate any tendency of the needles to core when they pierce the asealing idiaphragms or walls of the injection devices.

Further objects and advantages of the invention will become apparentwhen the following detailed description is considered in conjunctionwith the accompanying drawings.

In the drawings:

FIGURE 1 is a greatly enlarged, vertical, cross-sectional view of ahypodermic ampoule embodying a hypodermic needle made in accordance withthe present invention;

FIGURE 2 is an enlarged, fragmentary plan view of a sheet metal stripfrom which a hypodermic needle is progressively formed in accordancewith the invention by a series of punching and shaping operations, onlythe results of the first three forming operations being illustrated inthis view;

FIGURE 3 is a view similar to FIG. 2, showing the same sheet metal stripand indicating the fourth through the seventh forming operationsemployed in making needles in accordance with the invention;

FIGURE 4 is a further enlarged, fragmentary, longitudinal, sectionalview of the sheet metal strip of FIG. 2, taken as indicated by the line4-4 in FIGURE 2 at the location of the second forming operation;

FIGURE 5 is a similar, fragmentary, longitudinal, sectional view of thesheet metal strip of FIG. 2, taken as 1 indicated by the line 5--5 inFIGURE 2 at the location of the third forming operation;

FIGURES 6A, 6B, 6C, and 6D are similar, fragmentary, edge views of thesheet metal strip of FIG. 3, taken as indicated by the lines 6A6A,6B-6B, 6C-6C, and 6D6D, respectively, at the locations of the fourth,fifth, sixth, and seventh forming operations, respectively;

FIGURE 7 is a greatly enlarged end view of the pointed end of the needleat the conclusion of the seventh and last forming operation;

FIGURE 8 is a similarly enlarged side elevational view of the pointedend of the needle at the conclusion of the seventh and last formingoperation;

FIGURE 9 is another greatly enlarged side elevational view of thepointed end of the needle at the conclusion of the seventh and lastforming operation, this view being taken as indicated by the line 9--9in FIGURE 8;

FIGURES 10, 11, and 12 are vertical or longitudinal sectional views ofthe pointed end portion of the needle at the conclusion of the seventhand last forming operation, taken as indicated by the lines 10-10,11-11, and 1212, respectively, in FIG. 8;

FIGURE 13 is a greatly enlarged, fragmentary, plan view of a modifiedform of cannula blank that may be produced in the third formingoperation in order to obtain a more sharply pointed tip on the finishedneedle.

Before describing in detail the hypodermic needle formation whichcomprises one aspect of the invention, and its preferred method ofmanufacture, reference is first made to FIG. 1 which illustrates aparticular type of needle in a particular type of hypodermic ampoule. Itis to be understood at the outset that the specific construc tion ofthis ampoule forms no part of the present invention and will bedescribed only for the purposes of indicating one application for whichthe invention is particularly suitable and for explaining how the novelconfiguration of the pointed end of the needle effects functionalimprovements over prior art hypodermic needle constructions.

As shown in FIG. 1, the hypodermic ampoule has a body portion 20 in thegeneral form of an inverted cupshaped shell defined by an upper end wall21 and a circumferentially extending side wall. A peripherally outwardlyextending flange 22 integrally extends around the open end or mouth ofthe body 20, and a disk-like diaphragm 24 is sealed to this flange 22 soas to close the mouth of the body and form a fluid reservoir forcontaining the hypodermic liquid (not shown).

Enclosed entirely within the ampoule is a hypodermic needle 25constructed according to the present invention. In its preferredconstruction, the needle 25 has a circular, disk-like base 26 that isclamped adjacent the upper end wall 21 of the body 20 by a radiallyinwardly extending rib 27 so that a cannula 28 of the needle, whichextends axially from the base of the needle, is in substantial alignmentwith the axis of the ampoule body and has its pointed end projectingdownwardly in position to be forced through the diaphragm 24. A cannulaopening (not shown) through the base 26 of the needle and into theadjacent butt end of the cannula permits the hypodermic liquid to beevacuated from the ampoule through the cannula after it has pierced thediahragm.

As more specifically described in the copending application of RussellP. Dunmire, Serial No. 138,999, filed September 18, 1961 (now Patent No.3,094,987), the body portion 20 is constructed so that at least of thehypodermic liquid can be discharged from the ampoule when it is subjectto an axially directed collapsing force of not more than 10 or 12pounds. Provision is also made to prevent the ampoule body fromelastically expanding back toward its original shape after it has oncebeen collapsed, thereby avoiding the creation of a vacuum tending tosuck up or aspirate the hypodermic liquid back into the ampoule body.

To these ends, the preferred ampoule body 20 includes trees, are

a top section T defined by a flexible portion 30 of the circumferentialside wall and a bottom section B of larger diameter defined by arelatively rigid and inflexible wall portion 31. The portion 30 of theside wall that defines the top section T is tapered from a maximumthickness at its uper end to a minimum thickness at its lower end, whilethe portion 31 of the side wall that defines the bottom section B has athickness approximately twice the maximum thickness of the top side wallportion 30. The top and bottom sections T and B are connected by arelatively thin shoulder 32 which is no thicker and may be slightlythinner than the minimum thickness of the top side wall portion 30. Thisshoulder 32 defines the location of a primary hinge about which thecircumferential side wall of the ampoule is folded to initiatecollapsing thereof by a progressive inverting movement of the topsection downwardly within and against the bottom section when axialpressure is appliedto the ampoule.

The body construction is further shown as including a circumferentialnotch 33 around the upper end wall 21. This notch defines the locationof a secondary hinge which permits the top section T to be inverted andnested within the bottom section B with the upper end wall 21 of theampoule locked against the diaphragm 24.

As more specifically described in another copending application ofRussell P. Dunmire, Serial No. 139,000, filed September 18, 1961 (nowpatent No. 3,094,988), the diaphragm 24 is constructed to avoid a rapidbuild-up of hydraulic pressure within the liquid-filled shell and aconsequent hydraulic lock which could result in the ampoule body beingruptured before the hypodermic needle can be forced through thediaphragm at the initiation of an injection. Provision is also made toguide the hypodermic needle for entry into the skin in a directionsubstantially perpendicular thereto and to prevent an undesirable lossof the hypodermic liquid during an injection, as by leakage around theoutside of the needle where it pierces the diaphragm. To these ends, thediaphragm 24 has an outer annular portion 35, a thick, elongated,centrally located, needle guiding and liquid sealing gland 36, and arelatively thin, flexible, corrugated, intermediate portion 37connecting the gland and outer portion to permit relative movementtherebetween. An axial, needle receiving passage 38 extends into theupper end of the gland from inside the ampoule and terminates short ofthe opposite, lower end of the gland to form a thin, easily puncturablewall 39 closing the bottom of the passage. The lower end of the needlecannula 28 is slidably constrained within the passage with aninterference fit and with the pointed end of the needle being normallyspaced from the puncturable wall 39.

Due to the stiffness of the gland 36 and the length over which itcontacts the needle, an effective, peripheral, liquid seal is maintainedaround the needle under the hydraulic pressure created during dischargeof the ampoule. At the same time, the gland 36 is effective to supportand pilot the needle during an injection. This guided movement of theneedle minimizes the possibility of its being cocked and inserted at anoblique angle which might tear the skin and/or fail to penetrate to therequired depth for an effective injection.

The thin, flexible, corrugated wall section 37 of the diaphragm 24permits the gland 36 to move axially inwardly of the ampoule when thediaphragm is initially pressed against the skin. Because of thismovement of the gland, the distance through which the pointed end of thehypodermic needle must travel before it pierces the diaphragm wall 39and relieves the hydraulic pressure within the ampoule is relativelysmall. To the extent that inward movement of the gland 36 tends toreduce the interior volume of the liquid filled shell, the cor rugatedwall section 37 of the diaphragm is capable of bulging outwardlymomentarily until the needle has punctured the diaphragm and provided anescape path through the needle for the liquid. Consequently, it ispossible to it provide sufficient clearance between the pointed end ofthe needle and the gland wall portion 39 to avoid accidental puncturingof the diaphragm during handling of the ampoule, and at the same time,to prevent the creation of a hydraulic lock at the start of aninjection.

The diaphragm 24 is further shown to include a stiff, annular rib 40integrally extending from the upper surface of the outer diaphragmportion 35. This rib 40' is formed on a diameter such that it may betightly nested within the mouth of the ampoule body against its innerwall surface. During filling and assembly of the ampoule shell, the rib40 aids in locating the diaphragm 24 with respect to the body 20 so thatthe cannula 28 of the needle 25 can be aligned with and accuratelyinserted within the needle passage 38 of the gland 36. The rib 430 alsoforms a temporary liquid seal for preventing the hypodermic liquid fromspilling from the mouth of the ampoule body 20 prior to the diaphragmand body being permanently sealed together around their peripheries.

The hypodermic ampoule, including the body 20 and the diaphragmconstruction 24, may be made of any flexible material which is inert andretains its strength when exposed to the hypodermic liquid and whichwill not rupture and/ or tear as the ampoule is collapsed. Suitablematerials include tough but relatively flexible, elastomeric compounds,including plastics such as polyethylene and various other polyvinylcompounds and the like, plastic coated metal foils, and uncoated metalfoils which may be joined to form a leakproof liquid seal.

When, as in the preferred embodiment of the invention, the ampoule ismade of plastic and the body 20 and diaphragm 24 are joined by heatsealing, the circumferential flange 22 is preferably formed with anannular groove in which is seated a heat conducting metal ring 41. Asmore fully explained in the copending application of Russell P. Dunmire,Serial No. 252,272, filed January 15, 1963 (now abandoned) the metalring d1 facilitates a quick and localized application of heat to effectthe heat sealing of the body flange 22 and the outer annular portion 35of the diaphragm 24 so as to prevent the hypodermic liquid from beingdeleteriously aflected by the heat and the material of the ampoule frombeing seriously weakened by overheating.

In use, the ampoule is positioned with the diaphragm 24 against theskin, and an axially inwardly directed force is applied to the upper endwall 21, either manually with the thumb or by means of a mechanicalapplicator, as may be desired. The initial application of pressure tothe upper end wall forces the gland 36 inwardly relative to the body 20and causes the pointed end of the needle to enetrate the relatively thingland wall 39. Continued application of pressure results in thehypodermic needle being inserted into the skin and the body 20 beingcollapsed so as to discharge substantially all of the hypodermic liquidthrough the needle.

Reference is now made to the preferred. method of manufacturing thehypodermic needles This method contemplates forming a plurality of theneedles from a metal strip S by a continuous operation involving thesuccessive metal working and forming steps illustrated in FIGS. 25, and6A-6D.

For reasons which will hereinafter be made apparent, it is necessary tothe preferred practice of the invention that the metal of the strip Sfrom which the needles are formed possess work hardening properties.Another consideration is that the needles be resistant to corrosiveattack by hypodermic liquids. This latter criterion is of particularimportance when the needles are intended to be sealed within ampoulessuch as the one illustrated in FIG. 1, since the needles will usually beretained in contact with the hypodermic liquid for extended periods oftime.

Since the formulations of hypodermic liquids, and hence the corrosiveenvironment to which the hypodermic needles are subjected, vary widely,a particular metal cannot be arbitrarily selected and used in allapplications. Instead, it may frequently be necessary to test variousmetals in conjunction with particular hypodermic liquids before theoptimum metal can be accurately selected. However, stainless steels, andmore specifically the austenitic chromium-nickel steels, have been foundto be well suited for the purposes of the present invention since theynormally exhibit the required properties noted above. For exampleaustenitic chromium-nickel steels having a combined chromium.- nickelcontent of at least 23% with a minimum chromium content of 16% and aminimum nickel content of 7%, are noted for their rapid work hardening.In addition, when austenitic chromium-nickel steels are properly heattreated, they exhibit a wide range of passivity in corrosive solutions.A particular austenitic chromium-nickel steel which has been usedsuccessfully is A.I.S.I. type 304.

While stainless steel has been described as the preferred metal for thepurposes of the present invention, other work hardenable metals, such asbrass, plated carbon steel, and the like, also may be used in properenvironments.

As shown in FIG. 2, the first step in the preferred procedure of formingthe hypodermic needle 25 is to punch out a relatively small, generallyU-shaped piece ifrom the strip S so as to form a tongue 42 that extendsinto the punched out space. The tongue 42 is then work hardened in thetriangular area between the broken line 43 and the end of the tongue 42.This step of Work hardenin-g the tongue 42 may be carried out by a coldworking operation in which the bottom surface 44 of the tongue is coinedor swaged with suitable dies (not shown) so that the metal isprogressively reduced in cross-sectional thickness firom the fullthickness of the strip at the base of the triangular area to a minimumthickness near its tip (FIG. 4). The punched out space into which thetongue 42 extends facilitates the local cold working and work hardeningoperation by allowing the metal to flow laterally as the tongue iscoined and reduced in cross-sectional thickness.

In carrying out the invention, it is usually desirable to effect areduction in metal thickness in the tongue 42 of at least 50% and up to70% in order to assure that the coined metal is densified and materiallyhardened as compared to the rest of the strip. The specific amount ofcold Working which is required depends upon the particular metalemployed. However, in a typical instance where the metal is type 304stainless steel and the initial thickness of the strip S is in the rangeof .005 and .010 inch, the minimum metal thickness within the coinedarea of the tongue is from .002 and .003 inch.

In the next operation or, if desired, the next several operations, astrip-like cannula body blank 50 is defined and partially severed fromthe strip S. As shown in FIGS. 2 and 5, this cannula blank 50 is shapedto include a rectangular body portion 51 having parallel sides 52 and 53and a wedge shaped end portion 54 extending from one end of the bodyportion and defined by straight sides 55 and 56 that convergesymmetrically so that the end portion 54 has its point 57 lying on thelongitudinal axis of the strip-like blank. The included angle betweenthe converging sides 55 and 55 is an acute angle between about 55 and atmost, 65 according to the presently preferred embodiment of theinvention. It is to be understood, however, that the particularconfiguration of the pointed, terminal end of the cannula blank can bevaried in order to produce hypodermic needles which are specificallydesigned for special injections. In this blank forming operation, theoriginal U-shaped opening in the strip may be enlarged as shown tofacilitate trimthing of the converging edges 55 and 56 of the pointedend of the blank 50.

The other end of the blank 50, opposite from the point 57, is notsevered from the strip, but is an ularly bent in the region generallyindicated by reference numeral 58 so that the major part of the cannulablank extends substantially parallel to and slightly above the uppersurface of the metal strip 5.

It will be observed in FIGS. 2 and 5 that a substantial part of theWedge shaped or tapered end portion 54 is formed from the coined portionof the tongue 42 with the point 57 lying in that portion of the coinedarea which is approximately of minimum cross-sectional thickness. As aresult, the tapered end portion 54 has a thickness which tapers from thefull metal thickness of the body portion 51 of the blank 5%) to thepoint 57. Although the point 57 appears to be blunt in the enlargedcross-sectional view of FIG. 5, the actual metal thickness isapproximately .002 to .003 inch, and theretore, the point is as sharp orsharper than ground hypodermic needles of the prior art. With the acuteangle between the converging sides 55 and 56 described above, theextreme pointed end of the needle makes its initial penetration of theskin with ease and virtually painlessly.

The cannula body blank 54 may be formed by punching the strip S andtongue 42 against their under-surface with one or a series of suitablyshaped male dies (not shown) which may be moved upwardly intocooperating female dies (also not shown) so as to blank out the needlecannula with what is actually a shearing action. As will he recognizedby those familiar with metal working practices, when the dense, workhardened metal in the tongue 42 is acted on by the punching dies, themale die will only partially cut through the metal and will then simplybreak or fracture the metal. This action of forming the blank 50 and itspointed end portion 54 by bodily breaking it out of a hard, dense metalarea advantageously results in substantially burr-free edges along thesides of the blank out to the point 57. Another advantage, which is morefully explained below, is that the end portion 54 of the blank 50 istoed downward toward the plane of the strip S a slight amount, asindicated by angle a in FIG. 5.

In the next stage of the preferred manufacturing procedure, thesubstantially flat cannula blank 50 is semiformed by bending it into thegenerally Ushaped configuration designated by reference numeral 60 inFIGS. 3 and 6A. This is accomplished by suitable, cooperating dies (notshown) for symmetrically bending the blank 50 about its longitudinalaxis so that its sides 52 and 53 extend downwardly toward the plane ofthe strip S. Because of the narrowness of the blank adjacent the pointor apex 57 of the tapered end portion 54, and also because of the abovedescribed work hardening of the metal in this region, it tends to resistbending, leaving a more nearly fiat extreme end portion 59 closelyadjacent the point 57.

The semi-formed cannula blank 50 is then bent vertically, as illustratedin FIGS. 3 and 6B, so that it is substantially perpendicular to thestrip S, and, in a subsequent operation, is finish formed by bending thesides 52 and 53 into edge abutment to form the seam 61 (FIGS. 3, 7, and9), thus completing the tubular cannula section 28 with its pointed endor tip 57 and its nearly flat, and slightly toed-in extreme end portion59.

In the final step of manufacture illustrated in FIGS. 3 and 6D, agenerally circular portion of the strip S surrounding the upstandincannula Z8 is dished axially and centrally in the direction of the pointof the needle and its circular periphery is turned slightly in the samedirec tion to form the needle base 26 with a desired-configuration Whilethe base is severed from the strip.

As will be apparent to those skilled in the metal working art, all ofthe foregoing operations may be advantageously performed by aconventional, multi-slide, automatic punch press. It will be furtherapparent, that while the needle-forming process described aboveconstitutes an economical and practical method of manufacture, thepreferred procedure is subject to many variations by combining and/ orreversing certain of the individually described forming steps. Also,operations described above as being performed as a single deforming and/or severing step may be divided into a series of progressive deformingand severing steps as the particular tooling used may require.

Among the important advantages of the foregoing method of manufacture isthe elimination of the prior art operations of grinding, honing, anddeburring which were necessary to the formation of a sharp needle point.As noted above, the steps of preliminarily coining the metal strip andthen breaking out the tip of the cannula blank from the coined and workhardened metal results in a hard, substantially burr-free point. Only inspecial cases is it necessary to hone the point after the needle hasbeen severed from the strip. Further, since only the tip and convergingedges of the tongue-shaped cannula blank are hardened by cold working,the remainder of the blank being in a relatively soft, annealedcondition, the hypodermic needle may be progressively formed bysuccessive metal bending steps without requiring intermediate annealingoperations.

The elimination of the conventional grinding, deburring, honing, andannealing operations effects a substantial decrease in the cost ofproducing hypodermic needles.

Moreover, the method comprising the invention lends itself to themanufacture of hypodermic needles having more uniform dimensions andsharpness than could be obtained by the usual method in which the needlecannula was drawn and its point produced by grinding.

Other advantages afforded by the method of the invention result from thenovel configuration of the pointed end of the needle which is providedwith a sharp point and sharp cutting edges for facilitating penetrationof the needle through the wall of a plastic ampoule and its insertioninto the skin, as hereinafter discussed in more detail.

The exact formation of the pointed end of the needle is ditlicult todetermine precisely because of its very small size. However, it appearsfrom photomicrographs that the pointed end portion 54 of the needle hassharp, peripheral cutting edges that engage and cut into the skin with askin spreading action after the initial penetration of the sharp point57, and that this, together with the slightly teed-in and nearly flatspade-like extremity 59 of the pointed end, illustrated best in FIGS. 7and 8, appears to contribute to the improved skin penetrating action ofthe needle and to the absence of coring as the needle penetrates thediaphragm 24 of the ampoule.

As shown particularly in FIGS. 8 and 9, the sides or edge surfaces 55and 55 of the pointed end portion of the needle intersect at an acuteangle along a diametrical line 57:: (FIG. 8) at the point or apex 57.From this apex 57, the edge surfaces 55 and 56 diverge and twist axiallyand circumferentially of the needle cannula into substantially coplanaralignment at the locations designated by the line x-x in FIGS. 8, 9, and11, substantially where they reach the diametrically opposite points oftheir widest separation. From the line xx, the edge surfaces 55 and 56continue to twist and progressively converge again axially andcircumferentially of the needle cannula and toward the seam 6i. At theseam 61, the edge surfaces 55 and 55 again intersect along a diamctricalline 61a (FIGS. 79) that is parallel to their point or apex line ofintersection 570:. As will be apparent from FIG. 9, the angle ofintersection of the edge surfaces 55 and 56 varies from well in excessof at the intersection of the edges b and 56b to well under 45 at theintersection of the edges 55a and 56a, the average angular value asshown. being approximately 45.

The twisting of the edge surfaces 55 and 56, as described above,involves a 180 twist of each edge surface. Referring particularly toFIGS. 8, 10, and 11, it will be seen that the inner edges 55a and 55a ofthe edge surfaces 55 and 56 from the line 57a at the pointed extremityof the needle around in opposite directions to the line x-x are inposition to first contact the skin when the needle is inserted,perpendicular thereto. Also, down to the line xx from their intersection57a, the edge surfaces 55 and 5d slope downwardly and outwardly from theinner edges 55a and 56a, as is more readily apparent from FIG. 10.Because of this formation, it is believed that the inner edges 55a and55a initially act to sever the skin and the edge surfaces 55 and 56initially act to spread the skin apart as the needle is inserted.

At the line x-x, as best illustrated in FIGS. 8 and 11, the fullthickness of the metal along the edge surfaces 55 and So will be pressedagainst the skin, as occurs with conventionally ground bevel points.However, this occurs only for a minute part of the penetration. As theedge surfaces begin to converge toward the seam 61, the outside edges55!) and 56b have, in effect, been gradually turned over the inner edges55a and 56a sufiiciently to lead the edges 55a and 56a (FIGS. 8 and '12)and present sharp peripheral cutting edges to the skin so as to cutrather than tear the skin, and a virtually painless overall penetrationof the skin occurs. In this latter region, the edge surfaces 55 and 56slope downwardly and inwardly, as is more readily apparent from FIG. 10.

Probably because of the same cutting and initial spreading actiondescribed above, the coring problem encountered with conventionallybeveled points has been eliminated. The substantially flat extreme endportion 59 of the pointed end of the needle and the inward toeingthereof, as shown and described, also appear to be factors ineliminating coring. However, when the average value of the apex angle atthe line 57a between the side edges 55 and 56 is much less than shown inthe drawings (e.g., around 30 the needle of FIGS. 2-12 shows pronouncedcoring tendencies. This appears to be due to the fact that the anglebetween these side edges at 61:: is then also much more acute and tendsto act as a narrow slit so as to catch, hold, and, perhaps tear loosefragments of plastic. Thus, the particular angles referred to are moreor less critical.

Whatever the correct and complete explanation of the performance may be,the needles produced by the method of the present invention and havingthe particular configuration described avoid the coring problem andprovide virtually painless penetration of the skin. As a result, theyare ideally suited for use in the general type of ampoule shown in FIG.1.

Referring finally to the modified cannula blank 151 shown in FIG. 13 onan enlarged scale, the initial apex angle at the point 157 has beendecreased from about 45 (FIG. 2) to about 30 in order to obtain theeffect of a sharper point and even easier puncturing of the ampoulediaphragm and initial penetration of the skin. In order to do this andstill avoid the above described coring problem, however, it has beenfound necessary to curve the sides and 156 (corresponding to the sides55 and 56 in the blank of FIG. 2) outwardly in the region closelyadjacent the parallel sides 152 and 153 of the blank, while retainingthe planar configurations of the sides 155 and 156 over the remainderand major portions of their length, as shown. By doing this, the angleof intersection of the edge surfaces 155 and 156 with each other wherethey meet at the longitudinal butt seam of the finished needle may bekept large (as shown and described with reference to FIG. 9), and thecoring problem of the prior art is still avoided. However, as will bereadily appreciated, this renders the production of the point formingdies more difficult, and the benefits of the sharper point willgenerally be found to be so slight and questionable that they are notworth the added complication and possibly greater tendency to produceragged or irregular edges along the converging sides 155 and 156.

Although the improved needles of the invention are advantageouslyproduced from fiat strip stock by the procedure described in detail, itwill be apparent to those assaev skilled in the art that certainfeatures of the invention may be employed to advantage in the formationof points on articles other than needles, and in the formation of pointson seamless cannulae made by conventional procedures or on butt seamcannula tubing shaped from fiat strip stock before pointing. Forexample, solid needles for other than hypodermic purposes may beadvantageously pointed for some purposes by first cold working an end ofa round needle shank to harden and flatten it. Then, by the samepunching technique described with reference to FIG. 3, a hardened,slightly flattened point may be formed.

In the case of hypodermic needle cannulae and the like made fromconventional seamless tubing or seam tubing, the formation of a workhardened point might be performed as the final fabrication step, as bygrinding a conventional bevel, flattening and thinning the tip, andfinally trimming the deformed tip portion.

In view of the many possible applications of the principal features ofthe method phase of the invention, the term blank, as used herein in itsbroadest sense, is intended to include any form of unfinished article onwhich one or more final fabricating steps may be performed to produce afinished article.

From the foregoing description of my new method of making hypodermicneedles and the novel structure and characteristics of the resultingneedles, it will be apparent that the several objects and advantages ofthe invention have been achieved in a practical and efficient manner. Itwill also be apparent to those skilled in the art that various changesmay be made in the invention as specifically illustrated and describedherein, without departing from the invention as defined by theaccompanying claims.

What is claimed is:

1. A tubular hypodermic needle having a pointed end defined by a pair ofend edge surfaces that diverge axially of the cannula from an apex atits point While extending around the cannula in opposite directions fromone side to the opposite side thereof, said end edge surfacesintersecting at said apex and at said opposite side along linessubstantially normal to the axis of the cannula, and each of saidsurfaces twisting continuously about a median line thereof from saidapex to said intersection at the opposite side of the needle through anangle of 180, at least the apex and adjacent portions of said end edgesbeing hardened and thinned.

2. A tubular hypodermic needle having a pointed end defined by a pair ofend edge surfaces that diverge axially of the cannula from an apex atits point While extending around the cannula in opposite directions fromone side to the opposite side thereof, said end edge surfacesintersecting at said apex and at said opposite side along linessubstantially normal to the axis of the cannula, and each of saidsurfaces twisting continuously about a median line thereof from saidapex to said intersection at the opposite side of the needle through anangle of 180", at least the apex and adjacent portions of said end edgesbeing hardened and thinned, and the pointed end portion of the needlebetween said hardened and thinned end edge portions being toed inwardlytoward the axis of the needle.

3. A tubular hypodermic needle having a pointed end defined by a pair ofend edge surfaces that diverge axially of the cannula from an apex atits point while extending around the cannula in opposite directions fromone side to the opposite side thereof, said end edge surfacesintersecting at said apex and at said opposite side along linessubstantially normal to the axis of the cannula, and each ;of saidsurfaces twisting continuously about a median line thereof from saidapex to said intersection at the opposite side of the needle through anangle of 180, at least the apex and adjacent portions of said end edgesbeing hardened and thinned, and the pointed end portion of the needlebetween said hardened and thinned end edge portions being relativelyfiat compared to the circumferential 11.? curvature of the balance ofthe needle and being toed inwardly toward the axis of the needle.

4. A tubular hypodermic needle having a pointed end defined by a pair ofnon-planar edge surfaces that diverge axially and circumferentially ofthe needle cannula from an apex at its point and then converge axiallyand circumferentially of the needle cannula to an intersection on theopposite side of the needle cannula from said apex, said apex and saidintersection both extending linearly at their respective locations forthe thicknesses of the needle cannula wall at those locations andsubstantially radially of the needle cannula in a common diametricalplane.

5. A tubular hypodermic needle having a pointed end defined by a pair ofnon-planar edge surfaces that diverge axially and circumferentially ofthe needle cannula from an apex at its point and then converge axiallyand circumferentially of the needle cannula to an intersection on theopposite side of the needle cannula from said apex, said apex and saidintersection both extending linearly at their respective locations forthe thicknesses of the needle cannula wall at those locations andsubstantially radially of the needle cannula in a common diametricalplane, and said needle cannula having a longitudinal butt seamcontaining said intersection and lying in said common diametrical plane.

6. A tubular hypodermic needle having a pointed end defined by a pair ofnon-planar edge surfaces that diverge axially and circumferentially ofthe needle cannula from an apex at its point and then converge axiallyand circumferentially of the needle cannula to an intersection on theopposite side of the needle cannula from said apex, said apex and saidintersection both extending linearly at their respective locations forthe thicknesses of the needle cannula wall at those locations andsubstantially radially of the needle cannula in a common diametricalplane, and said needle cannula having a longitudinal butt seamcontaining said intersection and lying in said common diametrical plane,said butt seam being closed solely by abutment of the needle stock onopposite sides thereof without Welding or fusion of the metal onopposite sides of said seam.

7. A tubular hypodermic needle having a pointed end defined by a pair ofnon-planar edge surfaces that diverge axially and circumferentially ofthe needle cannula from an apex at its point and then converge axiallyand circumvferentially of the needle cannula to an intersection on theopposite side of the needle cannula from said apex, said apex and saidintersection both extending linearly at their respective locations forthe thicknesses of the needle cannula wall at those locations andsubstantially radially of the needle cannula in a common diametricalplane, and said non-planar end edge surfaces intersecting at said apexat an average angle of approximately 45 8. A tubular hypodermic needlehaving a pointed end defined by a pair of nonplanar end edge surfacesthat diverge axially and cir-cumferentially of the needle cannula froman apex at its point and then converge axially and circumferentially ofthe needle cannula to an intersection on the opposite side of the needlecannula from said apex, said apex and said intersection both extendinglinearly at their respective locations for the thicknesses of the needlecannula wall at those locations and substantially radially of the needlecannula in a common diametrical plane, and said non-planar end edgesurfaces intersecting at said intersection at an average angle well inexcess of 30.

9. A tubular hypodermic needle having a pointed end defined by a pair ofnon-planar end edge surfaces that diverge axially and circumferentiallyof the needle cannula from an apex at its point and then convergeaxially and circumferentially of the needle cannula to an intersectionon the opposite side of the needle cannula from said apex, said apex andsaid intersection both extending linearly at their respective locationsfor the thicknesses of the needle cannula Wall at those locations andsubstantially radially of the needle cannula in a common diametricalplane, and said non-planar end edge surfaces intersecting at said apexat an average angle of approximately 45 and intersecting at saidintersection at an average angle well in excess of 30.

10. A tubular hypodermic needle having a pointed end defined by a pairof non-planar edge surfaces that diverge axially and circumferentiallyof the needle cannula from an apex at its point and then convergeaxially and circumferentially of the needle cannula to an intersectionon the opposite side of the needle cannula from said apex, said apex andsaid intersection both extending linearly at their respective locationsfor the thicknesses of the needle cannula wall at those locations andsubstantially radially of the needle cannula in a common diametricalplane, and said non-planar end edge surfaces each twisting through anangle of substantially 180 between said apex and said intersection witha substantially uniform, gradual twist.

11. A tubular hypodermic needle having a pointed end defined by a pairof non-planar edge surfaces that diverge axially and circumferentiallyof the needle cannula from an apex at its point and then convergeaxially andcircumferentially of the needle cannula to an intersection onthe opposite side of the needle cannula from said apex, said apex andsaid intersection both extending linearly at their respective locationsfor the thicknesses of the needle' cannula wall at those locations andsubstantially radially of the needle cannula in a common diametricalplane, and said non-planar end edge surfaces each twisting through anangle of substantially 180 between said apex and said intersection witha substantially uniform, gradual twist that brings them intosubstantially coplanar alignment midway between said apex and saidintersection.

12. A tubular hypodermic needle having a pointed end defined by a pairof end edge surfaces that diverge axially of the cannula from an apex atits point while extending around the cannula in opposite directions fromone side to the opposite side thereof, said end edge surfacesintersecting at said apex and at said opposite side along linessubstantially normal to the axis of the cannula, and each of saidsurfaces twisting continuously about a median line thereof from saidapex to said intersection at the opposite side of the needle through anangle of 180, at least the apex and adjacent portions of said end edgesbeing workhardened and thinned.

13. A tubular hypodermic needle having a pointed end defined by a pairof end edge surfaces that diverge axially of the cannula from an apex atits point while extending around the cannula in opposite directions fromone side to the opposite side thereof, said end edge surfacesintersecting at said apex and at said opposite side along linessubstantially normal to the axis of the cannula, and each of saidsurfaces twisting continuously about a median line thereof from saidapex to said intersection at the opposite side of the needle through anangle of at least the apex and adjacent portions of said end edges beingworkhardened and thinned, and the pointed end portion of the needlebetween said work-hardened and thinned edge portions being toed inwardlytoward the axis of the needle.

14. A tubular hypodermic needle having a pointed end defined by a pairof end edge surfaces that diverge axially of the cannula from an apex atits point while extending around the cannula in opposite directions fromone side to the opposite side thereof, said end edge surfacesintersecting at said apex and at said opposite side along linessubstantially normal to the axis of the cannula, and each of saidsurfaces twisting continuously about a median line thereof from saidapex to said intersection at the opposite side of the needle through anangle of 180, at least the apex and adjacent portions of said end edgesbeing workhardened and thinned, and the pointed end portion of theneedle between said work-hardened and thinned end edge portion beingrelatively flat compared to the circumferential curvature of the balanceof the needle and being toed inwardly toward the axis of the needle.

References Cited by the Examiner UNITED STATES PATENTS 2,187,259 1/1940Barnhart 128221 2,769,443 11/ 1956 Dunmire 128--216 2,944,549 7/1960Alexander 128-216 3,071,135 1/1963 Baldwin et al. 128-221 3,082,769 3/1963 Palmer 128-221 FOREIGN PATENTS 1,225,009 2/ 1960 France.

RICHARD A. GAUDET, Primary Examiner. ROBERT E. MORGAN, Examiner.

1. A TUBULAR HYPODERMIC NEEDLE HAVING A POINTED END DEFINED BY A PAIR OF END EDGE SURFACES THAT DIVERGE AXIALLY OF THE CANNULA FROM AN APEX AT ITS POINT WHILE EXTENDING AROUND THE CANNULA IN OPPOSITE DIRECTIONS FROM ONE SIDE TO THE OPPOSITE SIDE THEREOF, SAID END EDGE SURFACES INTERSECTING AT SAID APEX AND AT SAID OPPOSITE SIDE ALONG LINES SUBSTANTIALLY NORMAL TO THE AXIS OF THE CANNULA, AND EACH OF SAID SURFACES TWISTING CONTINUOUSLY ABOUT A MEDIAN LINE THEREOF FROM SAID APEX TO SAID INTERSECTION AT THE OPPOSITE SIDE OF THE NEEDLE THROUGH AN ANGLE OF 180*, AT LEAST THE APEX AND ADJACENT PORTIONS OF SAID END EDGES BEING HARDENED AND THINNED. 